Long reach delivery of broadcast services using broadband optical sources and pre-compensation dispersion

• US 6,577,422 B1
• Filed: 02/18/1999
• Issued: 06/10/2003
• Est. Priority Date: 02/18/1998
• Status: Expired due to Fees

• Current Assignee: AT&T Corporation (AT&T, Inc.)
• Original Assignee: AT&T Corporation (AT&T, Inc.)
• Inventors: Frigo, Nicholas J., Iannone, Patrick P., Reichmann, Kenneth C.
• Primary Examiner(s): Pascal, Leslie
• Assistant Examiner(s): Phan, Hanh
• Application Number:
  US09/252,860
• Time in Patent Office: 1,573 Days
• Field of Search: 359/125, 359/127, 359/130, 359/161, 359/173, 359/137
• US Class Current: 398/49
• CPC Class Codes: H04B 10/25133 including a lumped electrical or optical dispersion compensator H04B10/2519, H04B10/2525 takes precedence
• CPC Class Codes: H04B 10/272 Star-type networks or tree-type networks
• CPC Class Codes: H04B 2210/254 before the transmission line, i.e. pre-compensation
• CPC Class Codes: H04J 14/0226 Fixed carrier allocation, e.g. according to service
• CPC Class Codes: H04J 14/0232 for downstream transmission
• CPC Class Codes: H04J 14/0246 using one wavelength per ONU
• CPC Class Codes: H04J 14/025 using one wavelength per ONU, e.g. for transmissions from-ONU-to-OLT or from-ONU-to-ONU
• CPC Class Codes: H04J 14/0282 WDM tree architectures

Abstract

A broadcast delivery system allows the delivery of broadband broadcast services over a WDM Passive Optical Network. These broadband services can be carried on optical broadband carriers or signals in a cost-effective manner by utilizing shared dispersion-compensated fiber (DCF) over a group of feeder lines or a group of PONs. A broadband optical signal is provided over a plurality of feeder lines. Each feeder line is connected to a remote node for distribution to subscribers. One dispersion-compensated fiber is shared for a plurality of feeder lines.

Claims

1. A broadcast delivery system comprising:

a plurality of passive optical networks (PONs), each passive optical network including at least an optical transmitter and a feeder line connected thereto;

a broadband optical source outputting a broadband optical signal; and

a dispersion compensating fiber having a first end connected to the broadband optical source and a second end connected to each of the plurality of PONs upstream of the feeder lines, the dispersion compensating fiber for dispersion compensating the broadband optical signal for each of the feeder lines in the plurality of PONs within an acceptable range, whereby further dispersion compensation of the broadband optical signal is not required downstream of the feeder lines.

2. The broadcast delivery system of claim 1 wherein the second end of said dispersion compensating fiber is connected via at least one other optical component to the plurality of PONs.

3. The broadcast delivery system of claim 2, said at least one other optical component comprising a splitter, wherein the second end of said dispersion compensating fiber is connected to an input of the splitter, and each of a plurality of outputs of the splitter are connected to one of the feeder lines.

4. The broadcast delivery system of claim 1 and wherein each said PONs further comprises a remote node connected to each of the feeder lines, the remote node receiving both an optical signal from the optical transmitter and the dispersion-compensated broadband optical signal from the broadband optical source via one of the feeder lines.

5. The broadcast delivery system of claim 4 wherein the remote node comprises a wavelength division multiplexing (WDM) device having an input coupled to one of the feeder lines, the WDM device having at least one output connected to a subscriber.

6. The broadcast delivery system of claim 5 wherein said WDM device comprises a waveguide grating router.

7. A broadcast delivery system comprising:

a first optical source having a first output for outputting a broadcast broadband optical signal;

a dispersion compensating fiber having an input connected to the first output for receiving the broadcast broadband optical signal from the first optical source;

a plurality of feeder lines each having a first end connected to an output of the dispersion compensating fiber, the dispersion compensating fiber for dispersion-compensating each of the plurality of feeder lines within an acceptable range;

a plurality of second optical sources, each having a second output for outputting a second optical signal to a corresponding feeder line;

a plurality of remote nodes, each having an input connected to a second end of its corresponding feeder line and each further having a plurality of remote node outputs, each remote node output coupled to a subscriber, whereby further dispersion compensation of the broadcast broadband optical signal is not required downstream of the first end of the feeder lines.

8. The broadcast delivery system of claim 7 wherein said remote node comprises a wavelength division multiplexing (WDM) device.

9. The broadcast delivery system of claim 7 wherein said remote node comprises a waveguide grating router.

10. The broadcast delivery system of claim 7 wherein each said second optical sources comprises a laser.

11. The broadcast delivery system of claim 7, wherein the first optical signal provides a first service and each second optical signal provides at least a second service to a subscriber.

12. A method of delivering broadcast services over a wavelength division multiplexed optical network, the method comprising:

generating a first optical signal;

generating a second optical signal, the second optical signal being a broadcast broadband optical signal output on a plurality of feeder lines;

coupling both the first optical signal and the second optical signal onto a first of the feeder lines;

using a dispersion compensating fiber upstream from the plurality of feeder lines to pre-compensate a dispersion of the second optical signal for each of the plurality of feeder lines within an acceptable range; and

routing the first and second optical signals on the first of the feeder lines to one or more subscribers based on wavelength, whereby further dispersion compensation of the second optical signal is not required downstream from the plurality the feeder lines.

13. The method of claim 12 wherein said routing further comprises:

routing the first optical signal to one or more selected subscribers based on the wavelength of the first optical signal; and

routing the dispersion compensated second optical signal to all subscribers connected to the plurality of feeder lines.

14. The method of claim 13 wherein said step of routing the dispersion compensated second optical signal further comprises:

spectrally slicing the second optical signal into a plurality of second optical signal portions, each second optical signal portion including the same information at a different wavelength; and

routing each second optical signal portion to one or more subscribers based on the wavelength of the second optical signal portion.

15. The method of claim 12 wherein the first optical signal delivers a first service to one or more selected subscribers and the second optical signal broadcasts a second service to all subscribers.

16. The method of claim 12 and further comprising:

grouping the plurality of feeder lines together based upon a similarity in a length of each of the feeder lines.

17. The method of claim 16 wherein said grouping further comprises:

grouping the plurality of feeder lines together based on length such that the dispersion compensating fiber will dispersion compensate all of the group of feeder lines within an acceptable range.

18. The method of claim 12 and further comprising:

using a common amplifier to amplify the second optical signal for the plurality of feeder lines.

19. A method of delivering broadcast services over a wavelength division multiplexed optical network, the method comprising:

generating a plurality of first optical signals for transmission to particular subscribers;

generating a second optical signal for transmission over a plurality of feeder lines, the second optical signal being a broadcast broadband optical signal for transmission to a plurality of subscribers including the particular subscribers;

coupling at least one of the plurality of first optical signals and the second optical signal on one of the feeder lines for transmission to a remote node;

using a dispersion compensating fiber upstream from the plurality of feeder lines to pre-compensate a dispersion of the second optical signal within an acceptable range, the dispersion compensating fiber having a one-to-many relationship with the feeder lines;

routing the coupled optical signals from the remote node to at least one of the particular subscribers based on wavelength, whereby further dispersion compensation of the second optical signal is not required downstream of the feeder lines.

20. A method for delivering broadcast services over a wavelength division multiplexed optical network, the method comprising:

providing a first service to at least one subscriber by transmitting a first optical signal over a plurality of passive optical networks, each passive optical network including a feeder line between an optical source and a plurality of subscribers;

providing a broadcast service to the plurality of the subscribers by transmitting a broadband optical signal over the plurality of passive optical networks; and

dispersion-compensating the broadband optical signal for a plurality of the feeder lines using a shared dispersion-compensated fiber disposed upstream of the plurality of feeder lines, whereby further dispersion compensation of the broadband optical signal is not required downstream of the feeder lines.